The present invention relates to catheters for insertion into a body lumen. More particularly, the present invention relates to a drug delivery catheter for use in the vascular system.
A wide variety of catheters have been developed in the prior art for percutaneous transluminal coronary or peripheral vascular applications. For example, balloon dilatation catheters for performing percutaneous transluminal coronary angioplasty are well known in the art.
In addition, a variety of catheters have been developed in the prior art for delivering therapeutic agents into the vascular system. For example, U.S. Pat. No. 4,636,195 to Wolinsky discloses the isolation of an arterial plaque between two ring balloons, and introduction of a solubilizing liquid therebetween. U.S. Pat. No. 5,049,132 to Shaffer et al. discloses an over the wire type catheter having an inner dilatation balloon disposed within an outer perforated drug delivery balloon. Similarly, U.S. Pat. No. 4,994,033 to Shockey et al. discloses concentric inner dilatation and outer delivery balloons disposed coaxially about an over the wire catheter.
In connection with other applications, U.S. Pat. Nos. 3,173,418 and 4,417,576 to Baran disclose double walled endotracheal cuffs having an external wall with multiple perforations for the administration of continuous or intermittent local endotracheal anesthesia. Fluid communication to the balloons is provided by way of fluid tubes which may be positioned within the endotracheal cuff wall.
In addition, a variety of patents appear to address the problem of inadequate perfusion associated with balloon dilatation angioplasty catheters, during the period of time that the balloon is inflated. For example, U.S. Pat. Nos. 4,877,031 to Conway et al. and 4,892,519 to Songer et al. disclose conventional balloon dilatation catheter designs, without any apparent drug delivery capability, in which a relatively low volume perfusion conduit is provided.
Finally, U.S. Pat. No. 4,423,725 to Baran et al. purports to disclose a combination dilatation and drug delivery design having a means for continued perfusion across the dilated balloon. Although stated to be useful in angioplasty, the catheter is also designed for use in tracheal, bladder and urethral treatments. If the Baran design were scaled down to an appropriate size for angioplasty use, only minimal perfusion would appear to be permitted by way of a plurality of side ports which communicate with the guide wire lumen.
Several of the catheters discussed above which have been approved by the FDA use a bolus method to deliver a liquid medication through an end hole or multiple side holes of the catheter. This method provides a mass delivery of the drug near the area of interest, and relies on the washing of the drug down the artery to deliver the drug to the desired location.
Other catheters, such as the one described in U.S. Pat. No. 5,087,244 to Wolinsky utilize a high pressure fluid delivery system which causes the drug to penetrate through the layers of the luminal wall beyond the artery's internal elastic lamina, referred to as intramural drug delivery.
Notwithstanding the foregoing, there remains a need for a drug delivery catheter, specially adapted for use in the relatively small diameter environments of the coronary and peripheral vascular systems. Optimally, the catheter will permit delivery of fluid medication to a site specific location in the vascular system or other body lumen.